Therapeutic gases may be applied to the body for the purpose of treating a variety of medical and non-medical conditions and producing other desirable effects. For example, gaseous nitric oxide (gNO) has been studied for its effects on infectious microorganisms, vasodilatation, skin diseases, respiratory infections, inflammation, bronchoconstriction, and the like. The biochemical mechanisms of action for gNO continue to be investigated.
In recent years, research has been directed to creating devices capable of delivering gNO from pressurized cylinders through distribution piping and delivery apparatuses in order to administer gNO at controlled doses to different tissue sites on or in the body. This approach is complicated by the relatively sophisticated electromechanical devices that are required to accurately and safely deliver the gNO. For example, the use of high pressure cylinders carries penalties of weight and size and requires the safe regulation of pressure down to pressures low enough to be suitable for application to tissues. Another limitation is that gas cylinders have elaborate distribution, management, recovery, and disposal needs, especially larger cylinders and cylinders that are intended to last for more than one therapy session. The complexity of this approach, therefore, can be costly.
Research and development also recently has been directed towards developing polymers with the capability of generating and releasing gNO. For example, some polymers can be stimulated to undergo an internal chemical reaction or conversion that releases gNO directly from the polymer. Typically, this internal chemical reaction or conversion occurs when the polymer is placed in contact with moisture. This approach may be limited by the complexity and cost of manufacturing such polymers.
Some polymers have the ability to absorb a therapeutic gas if they are placed in a gas rich environment and then release the gas at a later time if the surrounding level of the gas drops, consistent with the principles of diffusion. This method requires that the polymer be charged with the therapeutic gas before use and then applied to the desired delivery site. This approach may be limited by the polymer's potential to absorb the therapeutic gas, the requirement that the operator charge the polymer before use, and the dependence of the subsequent delivery on the surrounding gas concentration, temperature, and other environmental variables.
The description herein of problems and disadvantages of known apparatus, methods, and devices is not intended to limit the invention to the exclusion of these known entities. Indeed, embodiments of the invention may include one or more of the known apparatus, methods, and devices without suffering from the disadvantages and problems noted herein.